The Stanford Coronary Risk Intervention Project (SCRIP) is designed to determine if intensive modification of major risk factors for atherogenesis alters the rate of progression of coronary arterial disease. In order to avoid the problems of clinical endpoints and large patient groups plaguing other clinical trials, coronary arterial lesions are quantitated using angiography and a computer graphics system which provides a direct, objective endpoint for every patient; thus reducing sample size requirements. Patients who have coronary arteriography for clinical reasons and meet specific age, geographic and medical criteria, and consent to participate are enrolled. They are randomly assigned to two groups: one receives an aggressive multiple risk factor intervention program and the other follows the usual care of their physician. Those coronary vessel segments which have noncritical vascular lesions and were not altered by revascularization procedures, provide the substrate for assessing the effectiveness of risk factor modification. Coronary angiography is repeated four years after the baseline arteriogram. Computer quantitation of coronary luminal dimensions provides a sensitive test of changes in coronary atherosclerosis. Power calculations indicate a need to enter 300 patients and follow them for at least four years. Three hundred patients will be randomized during the initial 42 months of the project. Clinical status and risk factors are monitored at baseline, 12, 24, 36 and 48 months in all participants. Those randomized to aggressive risk factor management have close follow-up by study physicians and a "special intervention team." At the end of the third project year, 244 patients have entered the study with recruitment expected to be completed in six months. Risk factor status in those patients completing the first year in the project has not changed in the usual care patients, but has been reduced by an average of 33% in the special intervention patients. Follow-up data at one and two years indicate excellent adherence to the protocol with high probability of the project being successfully completed.